In addition to SEPT9, BMP3, and NDRG4 methylation biomarkers employed in the above two tests, aberrant methylation of other genes has been investigated as potential CRC biomarkers in the literature, including SDC2 (24, 25), SFRP1 (26–29), SFRP2 (29–31), GATA5 (32), ITGA4 (33–36), COL4A1 (33), COL4A2 (33), TLX2 (33), VIM (36–38), cg10673833 (39), GRIA4 (40), VIPR2 (41), EYA4 (42), MAP3K14-AS1 (42), MSC (42), CLIP4 (43), C9orf50 (43), and KCNQ5 (43). The gene discussed is COL4A2; the disease is colorectal carcinoma.